Hydraulically unbalanced wear plate



2 Sheets-Sheet 1 Pb 33 r 1 pence mph/{2,0 Hack March 2, 1965 P. SPENCERETAL HYDRAULICALLY UNBALANCED WEAR PLATE Filed June 19, 1963 M, W, WATTORNEYS HYDRAULICALLY UNBALANCED WEAR PLATE Filed June 19, 1963 2Sheets-Sheet 2 DEL VE'EY FEES-$11495 I INVENTORS 2 9 Pk 17/50 45? 6enaer b By 9G k8, 4%; add, 2 m, wk y h.

A TTORNE YS United States Patent 3,171,359 HYDRAULICALLY UNBALAN CEDWEAR PLATE Phillip B. Spencer, Royal Oak, and Philipp Becker, Utica,Mich, assignors to Thompson Ramo Wooldridge Inc., Cleveland, Ohio, acorporation of Ohio Filed June 19, 1963, Ser. No. 288370 Claims. (Cl.103126) This invention relates to improvements in high pressure positivedisplacement pumps and more particularly relates to such pumps having'an improved wear plate structure unbalanced to be forced against theend wall of the pumping chamber by the differential in pressure betweenthe inlet and outlet of the pump.

Heretofore pressure loaded gear pumps have maintained a close clearancebetween the gears and the end walls of the pumping chamber by the use ofa pressure loaded wear plate and the bleeding of pressure to the wearplate to bias the wear plate toward the end walls of the pumpingchamber.

With such pumping and wear plate structures, however, it has beendifficult to maintain the proper unbalance of the wear plate touniformly seal the wear plate to an associated end wall of the pumphousing except by complicated structures which materially increase thecost of the pump and make the pump impractical, due to expense, forinstallations requiring an efficient low cost pumping structure.

The present invention has as its principal object to overcome thesedifliculties by providing an improved wear plate structure andmaintaining the wear plate in firm contact with the associated end wallof the housing by subjecting the wear plate to the unbalanced intake anddelivery pressures of the pump over predetermined areas thereof.

Another object of the present invention is to provide a simplified andimproved form of pressure loaded gear pump having a novel form of wearplate structure maintained in position by the differential betweenintake and delivery pressure of the pump, and arranged with a viewtowards utmost simplicity in construction and operation.

A still further object of the invention is to provide a simple andimproved form of gear pump structure having a pressure loaded wearplate, in which passageway means are provided to bias the wear plateinto sealing engagement with the end wall of the housing by thedifference between intake and delivery pressure and in which the wearplate may loosely fit along the peripheral wall of the pumping chamberand is maintained in sealing contact therewith by subjecting an edgeportion of the wear plate to delivery pressure.

Another object of the invention is to improve upon the pressure loadedgear pumps heretofore constructed by providing a passageway means fromthe inlet into the pumping chamber subjecting one side of the wear plateto inlet pressure and other passageway means in communication with theoutlet from the pumping chamber subjecting a portion of the area of thewear plate to delivery pressure.

Still another object of the invention is to provide a means forunbalancing the wear plate of a pressure loaded gear pump andmaintaining the wear plate in sealing engagement with the associated endwall of the pumping chamber by providing passageway means incommunication with the inlet to the pumping chamber and extending alongthe wear plate in opposite directions from the inlet end of the pumpingchamber to a region close to the high pressure region of the pumpingchamber, and by providing other passageway means on the opposite side ofthe wear plate from the first mentioned passageway means and extendingin opposite directions from the outlet from Fee the pumping chamberalong the Wear plate to the low pressure side of the pumping chamber andunbalancing the wear plate toward the end wall of the pumping chamber toaccommodate fluid at discharge pressure to firmly hold the wear plateagainst the end wall of the pumping chamber.

A still further object of the invention is to provide an improved formof wear plate for pressure loaded gear pumps having a groove in one sidethereof in communication with the inlet to the pumping chamber andextending along the side of the wear plate abutting an end wall of thepumping chamber to a region close to the high pressure region of thechamber, and having a groove on the opposite side thereof incommunication with the outlet from the pumping chamber and extendingalong the wear plate in opposite directions from the outlet toward thelow pressure side of the pumping chamber, and having relief along theedge of the wear plate in the region of the outlet and subjecting thewear plate along its edge to fluid under pressure to provide sealingcontact between the wear plate with the peripheral wall of the pumpingchamber at the intake side thereof.

These and other objects of the invention will appear from time to timeas the following specification proceeds and with reference to theaccompanying drawings wherein:

FIGURE 1 is a sectional view taken through a gear pump showing a wearplate constructed in accordance with the principles of the presentinvention in abutting engagement with one wall of the pumping chamber;

FIGURE 2 is a partial fragmentary sectional view taken transverselythrough the pumping chamber and showing certain details of the wearplate structure;

FIGURE 3 is a partial fragmentary sectional view taken substantiallyalong line III-lII of FIGURE 2 and showing a part of the wear platestructure; and

FIGURE 4 is a partial fragmentary transverse sectional view takenthrough a pressure loaded gear pump constructed in accordance with theprinciples of the present invention and illustrating a modified form inwhich the invention may be embodied.

In the embodiment of the invention illustrated in the drawings, we haveshown in FIGURE 1 a pump housing 10, one end of which may be closed byan end plate (not shown) in a conventional manner and having an innerend wall forming an end wall of a pumping chamber 11. The pumpingchamber 11 has an opposite end wall 12 and a peripheral wall 13 in thegeneral form of a figure 8. An inlet 15 leads through the peripheralwall 13 into the region of juncture of the peripheral circumferentialwall portions thereof. The housing 10 also has an outlet 16 leadingtherefrom in aligment with the inlet, and on the opposite side of thepumping chamber from the inlet.

A drive gear 17 is shown in FIGURE 4, as having the usual radiallyextending circumferentially spaced teeth 18 having close sliding contactwith the upper circumferential wall portion of the pumping chamber 11.The drive gear 17 is suitably secured to a transverse shaft 19journalled in the housing 10 on a bearing 20 on one of its ends andsuitably journalled in the end cover (not shown) at its opposite end.

The gear 17 meshes with and drives a gear 21, the teeth of which haveclose sliding contact with the lower circumferential wall portion of thepumping chamber. The gear 21 is suitably mounted on a shaft 22 suitablyjournalled in the housing 10 and end cover therefor, in a conventionalmanner.

As shown in FIGURES l and 2 a wear plate 25 is interposed between thesides of the gears 17 and 21 and the end wall 12 of the pumping chamber.It is customary to pressure load a gear pump at only one end, althoughunder certain conditions it may be desirable to have two wear plates,one abutting each end wall of the pumping chamber. Where two wear platesare used, the construction and operation of each wear plate is the same,so the construction of one wear plate only need herein be shown ordescribed in detail.

The wear plate 25 may be of a laminated construction having a bearingface 25 facing and slidably engaged by the gears 17 and 21. While thewear plate 25 is shown as being of a laminated .construction, a bearingsurface for the gears 17 and 21 may be coated thereon by a conventionalcoating process, if desired.

The wear plate 25 is shown in FIGURE 1 as being in the general form of afigure 8 in plan, conforming to the peripheral wall 13 of the pumpingchamber'and having a relatively loose fit therein. A groove 27 incommunication with the inlet 15 extends inwardly along the plate at theintersection of the circumferential portions of said plate. The groove27is on the side of the wear plate 25 facing the wall 12 and hascommunication with grooves 29, 2 extending in opposite directions fromthe groove 27 and generally conforming to the periphery of the plate 25in radially inwardly spaced relation with respect to the peripherythereof. The grooves 29, as shown in FIGURE 3, extend from the intake orsuction side of the pump and terminate at diametral line A in the regionof the high pressure side of the pump, it being of advantage to extendthe grooves close to the point where the gears build up the maximumpressure of fluid for discharge through the outlet 16.

Similar grooves 39 are formed in the opposite side of the wear plate 25from the grooves 27 and 29 and extend in opposite directions from thedischarge side of the pump along the wear plate in general conformity tothe periphery of the wear plate to diametral lines B at the suction sideof the pumping chamber. Discharge pressure acting on the wear plate 25along the grooves 30 will thus unbalance the wear plate in a directionof the hydraulic force H and thereby keep the wear plate from moving anduniformly contact the wear plate with the wall 12 of the pumpingchamber.

The edge of the Wear plate 25 along the pressure side of the pumpingchamber, is shown in FIGURE 3 as being relieved as by a bevel 33extending in opposite directions along the discharge or pressure side ofthe pumping chamber from the juncture of the circular wall portions ofthe wear plate and gradually merging into the wear vplate. This reliefor beveled edge forms an increased area surface along the pressure edgeof the wear plate upon which the fiuid at discharge pressure acts andforces the wear plate in the direction H against the peripheral wall ofthe pumping chamber and thereby counteracts for a relatively loose fitof the wear plate and forces the wear plate to form a contact seal withthe peripheral wall of the pumping chamber at the intake side thereof.

In the modified form of the invention shown in FIG- URE 4 a groove 35 isformed in an end wall 12:: of the pumping chamber. The groove 35 may beof the same general form as the grooves 27 and 29, 29 and extends alongthe wall of the pumping chamber to a position as close to the highpressure region of the pump as possible. A groove 36 is shown as beingformed in a wear plate 250 and opening toward the gears 17 and 21 andhaving communication with the pressure side of the pump and extendingabout the wear plate to the same extent the grooves 30 extend along thewear plate 12.

It may be seen from the foregoing that we have improved upon the highpressure gear pumps heretofore in use by providing a simplified form ofunbalanced wear plate, in which the side of the wear plate abutting theend Wall of the pumping chamber is subjected to intake pressure orsuction, and the opposite side of which is subjected to the pressure ofthe discharge side of the pump, and that the portions ofthe wear platesubjected to positive and negative pressure are so unbalanced as toassure firm contact of the wear plate with the end Wall of the pumpingchamber.

It may further be seen that the wear plate is so constructed that itneed not be tightly fitted into engagement with the wall of the pumpingchamber and may be relatively loose in the pumping chamber and forcedagainst the wall of the pumping chamber by the delivery pressure of thefluid to form a contact seal with the peripheral wall of the pumpingchamber and reduce the losses in flow that would otherwise be presentwith a loose fitting wear plate.

While we have herein shown and described several forms in which ourinvention may be embodied, it may readily be understood that variousmodifications and variations in the invention may be attained withoutdepartirg from the spirit and scope of the novel concepts there- 0 Weclaim as our invention:

1. In a high pressure gear pump,

a housing having a hollow interior portion forming a pumping chamberhaving parallel spaced end walls and an internal peripheral wall in thegeneral form of a figure 8,

a pair of shafts rotatably journalled in said housing and having meshinggears mounted thereon and disposed in said pumping chamber between saidside walls and in close contact with said intern al peripheral wall andhaving intersecting pitch circles,

an inlet into said pumping chamber in axial alignment with said pitchcircles at the point of intersection thereof,

said gears and pumping chamber establishing a suction area in the regionof said inlet,

an outlet from said pumping chamber leading from the opposite side ofsaid pumping chamber from said inlet and in axial alignment therewith,

said gears and pumping chamber establishing a high pressure area in theregion of said outlet, at least one wear plate in said pumping chamberfree from said shafts and abutting an end wall of said pumping chamberand generally conforming to the peripheral wall of said pumpingch-amber,

a groove extending along the side of said wear plate faclng an adjacentend wall of said pumping chamher and opening toward said end Wall,

a passageway in said Wear plate affording communication from said inletto said groove,

said groove generally conforming to the periphery of said wear plate andthe internal wall of said pumpmg chamber, and being spaced closer tosaid peripheral wall than said shaft, and terminating at the highpressure area of said pumping chamber and subjectmg the side of saidwear plate facing said end wall to inlet pressure,

a second groove in the side of said wear plate facing sa d gears andopening to said gears and being in al gnment with said first groove andextending along said wear plate in opposite directions from said outletand terminating at the suction area of said pump,

said second groove having communication with said outlet and subjectingthe side of said wear plate facing said gears to discharge pressure,

whereby the imbalance of inlet and discharge pressure in said grooves onopposite sides of said wear plate biases said wear plate into firmengagement with said end Wall of said pumping chamber.

2. A high pressure gear pump in accordance with claim 1 wherein the wearplate has a bearing face thereon on the side thereof adjacent saidgears.

3. A high pressure gear pump in accordance with claim 1 wherein the wearplate has a relatively loose fit in said pumping chamber and has acha-rnfered edge on the side thereof facing said outlet to forc said Wer plate into sealing contact with the peripheral wall of said pumpingchamber by the force of the pressurized fluid in the high pressureregion of said outlet.

4. In a high pressure gear pump,

a housing having a hollow interior portion foming a pumping chamberhaving opposite end walls and an internal peripheral wall in the generalform of a figure 8,

a pair of meshing gears in said pumping chamber between said side wallsand in close contact with said peripheral wall and having intersectingpitch circles,

shafts for said gears journalled in said housing and mounting said gearsfor rotation within said pumping chamber,

an inlet into said pumping chamber in axial alignment with the pitchcircles of said gears and facing said gears as they come out of mesh,

said gears and pumping chamber establishing a suction area in the regionof said inlet,

an outlet from said pumping chamber leading from the opposite side ofsaid pumping chamber fIOirl said inlet and in axial alignment therewith,

said gears arid jumping chamber establishing a pressure area in theregion of said outlet,

at least one wear plate in said pumping chamber abutting an end wallthereof and spaced radially from sai shafts and generally conforming tothe peripheral Wall of said pumping chamber,

a groove in the side of said wear plate facing said gears and leadingalong said wear plate in opposite directions from said discharge outletand spaced closer to the periphery of said wear plate than said shaftsand generally conforming to the periphery of said Wear plate andinternal wall of said pumping chamher and terminating at the suctionarea of said pump and subjecting the face of said wear plate facing saidgears to discharge pressure, and a groove in the end Wall of saidpumping chamber abutted by said wear plate opening towards said wearplate and in axial alignment with the groove in said wear plate andhaving communication with said inlet and extending along said end walland generally conforming to the periphery of said wear plate andinternal wall of said pumping chamber and terminating at the pressureregion of said pumping chamber and subjecting the face of said wearplate facing said end Wall to inlet pressure, whereby the imbalance ofinlet and discharge pressure on said wear plate biases said wear plateinto sealing engagement with the adjacent end wall of said pumpingchamber.

5 A high pressure gear pump in accordance with claim 4 in which the sideof the wear plate facing the meshing gears has a bearing face thereonfor the side faces of said gears, and in which the edge of the wearplate facing the outlet is c hamfered to effect the forcing of the wearplate into sealing engagement with the peripheral wall of the pumphousing.

References fired in the file of this patent UNITED STATES PATENTS2,682,836 Orr July 6, 1954 2,864,315 Udale Dec. 16, 1958 2,870,720Lorenz Jan. 27, 1959 2,997,960 Kimijima et a1. Aug. 29, 1961 3,057,303Lauck Opt. 9, 1962

1. IN A HIGH PRESSURE GEAR PUMP, A HOUSING HAVING A HOLLOW INTERIORPORTION FORMING A PUMPING CHAMBER HAVING PARALLEL SPACED END WALLS ANDAN INTERNAL PERIPHERAL WALL IN THE GENERAL FORM OF A FIGURE 8, A PAIR OFSHAFTS ROTATABLY JOURNALLED IN SAID HOUSING AND HAVING MESHING GEARSMOUNTED THEREON AND DISPOSED IN SAID PUMPING CHAMBER BETWEEN SAID SIDEWALLS AND IN CLOSE CONTACT WITH SAID INTERNAL PERIPHERAL WALL AND HAVINGINTERSECTING PITCH CIRCLES, AN INLET INTO SAID PUMPING CHAMBER IN AXIALALIGNMENT WITH SAID PITCH CIRCLES AT THE POINT OF INTERSECTION THEREOF,SAID GEARS AND PUMPING CHAMBER ESTABLISHING A SUCTION AREA IN THE REGIONOF SAID INLET, AN OUTLET FROM SAID PUMPING CHAMBER LEADING FROM THEOPPOSITE SIDE OF SAID PUMPING CHAMBER FROM SAID INLET AND IN AXIALALIGNMENT THEREWITH, SAID GEARS AND PUMPING CHAMBER ESTABLISHING A HIGHPRESSURE AREA IN THE REGION OF SAID OUTLET, AT LEAST ONE WEAR PLATE INSAID PUMPING CHAMBER FREE FROM SAID SHAFTS AND ABUTTING AN END WALL OFSAID PUMPING CHAMBER AND GENERALLY CONFORMING TO THE PERIPHERAL WALL OFSAID PUMPING CHAMBER, A GROOVE EXTENDING ALONG THE SIDE OF SAID WATERPLATE FACING AN ADJACENT END WALL OF SAID PUMPING CHAMBER AND OPENINGTOWARD SAID END WALL, A PASSAGEWAY IN SAID WEAR PLATE AFFORDINGCOMMUNICATION FROM SAID INLET TO SAID GROOVE,